To get an early start for your herb garden, you can cultivate seedlings in your house in early spring. I do this with basil, coriander, parsley, cress, and tarragon. The first four worked great, taragon is a bit difficult and I needed 3 starts to get it right.
Be sure to use a seed starter potting mix. I just use normal flower pots and spread the seeds sparingly. Depending on the type you need to cover them with 1 to 2 cm of soil others need light induced germination so you just have to spread them evenly over a flat soil bed and press them gently. Be sure to keep the seedlings moist and to provide light. A window sill is perfect. Don’t let them get too cold, but to warm is also not good. Something about 18 to 23°C is typically fine.
Many sources recommend pricking out the seedlings after 2 to 4 weeks – that is to repot them separately to give them enough space. I never did that, trying to use the seeds sparingly to start with. When the seeds have grown 5 to 10 cm you can just pot them out in the garden (I recommend high-rise bed – more to this later). If you use tiny compostable pots (see image), you can just weed out weak plants and dig the pots directly in the garden soil.
Be sure to set up new pots of your favorite herbs every 2 weeks so you get great harvest for a long time.